Starring: Robert Conrad, Dick Cangey, Ross Martin, Whitey Hughes
The Night of the Infernal Machine - S2-E14
Revealing mistake: Right after Zeno Baroda says, "M'Guigan, I'm going to kill you," he shoots at the door. Before the bullet is discharged, one can see the door is already damaged where the door is about to be shot. Also, one can see the streak (moving from the left to right) of the prop used to cause more damage on the door from the bullet's impact. (00:27:30)
The Night of the Brain - S2-E21
Revealing mistake: Mr. Braine screams as his steam-powered chair crashes into the bandstand. If you look closely at the next shot, just before the explosion, you can see that the dummy now in the chair has its head bowed forward. It also has light brown hair, rather than Mr. Braine's silver hair. (00:47:10)
The Night Dr. Loveless Died - S3-E4
Trivia: Dr. Loveless' uncle's name, "Liebknicht", is, aside from the addition of the letter "k", German for "Loveless".